Definition 1.3 [1]} Let \(S\)  be a set of distinct elements of \(\mathbb {C}\cup \lbrace \infty \rbrace \)  and \(k\)  be a non-negative integer or \(\infty \) . We denote by \(E_{f}(S,k)\)  the set \(\cup _{a\in {S}}E_{k}(a;f)\) . Clearly \(E_{f}(S)=E_{f}(S,\infty )\)  and \(\overline{E}_{f}(S)=E_{f}(S,0)\) .
